Refrigerated air freight container

ABSTRACT

An electrically powered air freight container ( 1 ) includes an insulated housing ( 2 ) and a refrigeration unit ( 3 ). The refrigeration unit ( 3 ) is powered by a voltage and frequency converter which receives electrical power at one voltage and frequency and converts that power to a voltage and frequency which is appropriate to power the refrigeration unit ( 3 ).

FIELD OF THE INVENTION

[0001] The present invention relates to refrigerated freight containerto be carried by aircraft. In particular, the invention relates to suchcontainers wherein the contents of the container may be refrigeratedwhile the container is both within the aircraft and while the containeris on the ground in transit to or from an aircraft.

BACKGROUND OF THE INVENTION

[0002] A number of attempts have been made to produce a refrigeratedaircraft freight container which will operate while in an aircraft andwhile in transit on the ground.

[0003] U.S. Pat. No. 3,889,486 to Grayson W. Minckley discloses aremovable refrigeration system which uses dry ice. Insulation panelsline the interior surfaces of the cargo container and support each otherso that no connections between the panels and the cargo container arenecessary. The panel lining the door of the cargo container is forcedagainst the other insulation panels by the force used to close the doorof the cargo container, forming an enclosed space sealed from theatmosphere. A box carrying dry ice is carried in a corner of theenclosed space and is insulated from the bulk of the enclosed space.Inlet and outlet ports allow air to flow over the box. A slidable coveris provided over the outlet port to regulate the amount of air flowingaround the box.

[0004] U.S. Pat. No. 4,276,752 to Peter R. Modler, et. al. discloses aninsulated container with an insulated bunker which includes a heatexchanger portion located within one of the to corners of the freightcontainer. The bunker holds a coolant, such as dry ice. Vapour from thecoolant is vented to the outside of the container.

[0005] U.S. Pat. Nos. 5,473,908 and 5,819,550 to Louis P. Saia andRussell Andrews discloses transportable containers which are cooled bythe boiling off of a liquid refrigerant.

[0006] U.S. Pat. No. 5,491,979 to Harald Kull et. al. discloses arefrigerated food trolley for an aircraft. The trolley has a heatexchange surface directly connected to a coolant flow circuit in thetrolley. When the trolley is parked in a parking space for example in anaircraft galley, the heat exchange surface of the trolley is in heatexchange contact with a heat exchanger connected to a centralrefrigerant circuit in the aircraft.

[0007] U.S. Pat. No. 5,369,960 to Hans-Juergen Mueller, et. al.discloses an insulated container including a coolant circuit, whichcircuit is connected to a source of coolant fluid within the aircraft.

[0008] In contrast, the present invention seeks to provide arefrigerated aircraft freight container which can be used both in anaircraft and removed from the aircraft, and which does not need to becharged with solid or liquid refrigerants.

[0009] The present invention also seeks to provide a refrigeratedaircraft freight container which does not require connections to arefrigerant source mounted in the aircraft.

SUMMARY OF THE INVENTION

[0010] The present invention accordingly provides a refrigerated airfreight container which includes:

[0011] an insulated housing having an interior region;

[0012] a refrigerator unit which is mounted on the housing forrefrigerating the interior region of the housing, which refrigeratorunit includes:

[0013] an electrically powered compressor which operates at a givenpower supply voltage and frequency;

[0014] evaporator means; and

[0015] condenser means,

[0016] the refrigerated air freight container further including avoltage and frequency converter which receives electrical power at afirst voltage and frequency and converts that electrical power to asecond voltage and frequency which is the given power supply voltage andfrequency of the compressor.

PREFERRED FEATURES OF THE INVENTION

[0017] Preferably, the first voltage which is received by the voltageconverter may be within a range of voltages.

[0018] Preferably that range of voltages includes 240 volts and 115volts.

[0019] Preferably, the first frequency which is received by the voltageconverter may be within a range of frequencies.

[0020] Preferably, the second voltage and frequency may be directcurrent.

[0021] It is also preferred that the refrigerator unit is removablymounted on the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is an isometric view of a refrigerated air freightcontainer according to one embodiment of the present invention.

[0023]FIG. 2 is a cross-sectional view of the insulated housing of FIG.1.

[0024]FIG. 3 shows a detail of the connection between the insulatedhousing and the refrigerator unit of FIG. 1.

[0025]FIG. 4 shows details of the internal confirmation of therefrigerator unit of FIG. 1.

[0026] In order that the invention may be more readily understood,preferred embodiments of it will now be described with reference to thedrawings.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0027]FIG. 1 shows a refrigerated air freight container 1.

[0028] The container 1 includes an insulated housing 2 and arefrigerator unit 3. In the present embodiment of the invention, therefrigerator unit 3 is readily detachably mounted to the insulatedhousing 2 as described below.

[0029] In alternative preferred embodiments of the invention, therefrigerator unit 3 is permanently attached to the insulated housing 2.

[0030] The insulated housing 2 according to the embodiment of FIGS. 1 to3 includes insulated side, bottom and top walls configured to generallyconform to the shape required of a standard airfreight container. Oneend wall includes doors 4 which are kept closed by the latchingmechanism 6.

[0031] There is a rectangular opening 7 in the top of the insulatedhousing 2. The peripheral edges 8 of the opening are countersunk at 9. Aperipheral ledge 11 extends from the refrigerator unit 3 for supportingthe refrigerator unit 3 on the countersunk edges 9. A deformable seal 12retains the refrigerator unit 3 firmly in place in the opening 7 andaids in the insulation of the interior of the housing 2 from theexternal environment. Preferred materials for the seal 12 include butylrubber and silicon rubber.

[0032] The mounting of components within the refrigerator unit 3 isshown in FIG. 4. According to the present embodiment of the invention,the refrigerator unit 3 includes two refrigeration circuits. There aretwo condensers 11 and two electrical components boxes 12 mounted withinthe refrigerator unit 3. There are two evaporators (not illustrated) andtwo fans (not illustrated) mounted on the underneath side of therefrigeration unit 3.

[0033] Valving (not illustrated) allows either or both of the condensers11 to supply refrigerant to either or both of the condenser/evaporatorpairs. Both of these refrigeration circuits are used for freezing, andonly one of these circuits is used for chilling.

[0034] The present embodiment of the invention has two electrical powerinlets. The first of these is adapted to plug into the Australianstandard 240 volt/50 Hz mains power supply. The second of these powerinlets is adapted to plug into the aircraft standard three phase 115volt/400 Hz power supply. The supply from this second power inlet isrectified, and the rectifier supplies power to two independentconverters. The converters each output power at 240 volts/50 Hz. Each ofthe converters powers one refrigeration circuit.

[0035] According to alternative preferred embodiments of the invention(not illustrated) the invention has only one electrical power inlet. Thesupply from this one inlet is rectified and converted to an appropriatevoltage and frequency to power the refrigeration circuits.

1. A refrigerated air freight container which includes: an insulated housing having an interior region; a refrigerator unit which is mounted on the housing for refrigerating the interior region of the housing, which refrigerator unit includes: an electrically powered compressor which operates at a given power supply voltage and frequency; evaporator means; and condenser means, the refrigerated air freight container further including a voltage and frequency converter which receives electrical power at a first voltage and frequency and converts that electrical power to a second voltage and frequency which is the given power supply voltage and frequency of the compressor.
 2. A refrigerated air freight container as claimed in claim 1 wherein the first voltage which is received by the voltage converter may be within a range of voltages.
 3. A refrigerated air freight container as claimed in claim 2 wherein the range of voltages includes 240 volts and 115 volts.
 4. A refrigerated air freight container as claimed in any one of the preceding claims wherein the first frequency which is received by the voltage converter may be within a range of frequencies.
 5. A refrigerated air freight container as claimed in any one of the preceding claims wherein the second voltage and frequency may be direct current.
 6. A refrigerated air freight container as claimed in any one of the preceding claims wherein the refrigerator unit is removably mounted on the housing. 